linux-kernel - [PATCH v2 2/3] VFIO: use ACCESS_ONCE() to guard access to dev->driver

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Date:	Fri, 16 Nov 2012 00:43:17 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	Alex Williamson <alex.williamson@...hat.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Jiang Liu <jiang.liu@...wei.com>,
	Joerg Roedel <joerg.roedel@....com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Hanjun Guo <guohanjun@...wei.com>
Subject: [PATCH v2 2/3] VFIO: use ACCESS_ONCE() to guard access to dev->driver

Comments from dev_driver_string(),
/* dev->driver can change to NULL underneath us because of unbinding,
 * so be careful about accessing it.
 */

So use ACCESS_ONCE() to guard access to dev->driver field.

Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
---
 drivers/vfio/vfio.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 3359ec2..0090212 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -465,8 +465,9 @@ static int vfio_dev_viable(struct device *dev, void *data)
 {
 	struct vfio_group *group = data;
 	struct vfio_device *device;
+	struct device_driver *drv = ACCESS_ONCE(dev->driver);
 
-	if (!dev->driver || vfio_whitelisted_driver(dev->driver))
+	if (!drv || vfio_whitelisted_driver(drv))
 		return 0;
 
 	device = vfio_group_get_device(group, dev);
-- 
1.7.9.5

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